This application claims the benefit of German patent application DE P 100 48 792.0, filed Oct. 2, 2000, herein incorporated by reference.
The present invention relates to a thermostatic valve, especially such a valve adapted for the cooling system of a vehicle with an internal-combustion engine. More particularly, the present invention relates to such a thermostatic valve having a valve housing, a temperature-sensitive operating element in an operating element housing affixed stationarily on the valve housing, and a closure member adjustably controlled by the operating element. The valve housing comprises a radiator connection opening, an engine connection opening and an additional auxiliary connection opening, whereby a radiator flow of the cooling system coolant can be established between the radiator connection opening and the auxiliary connection opening, a short circuit flow of the cooling system coolant can be established between the engine connection opening and the auxiliary connection opening, and the radiator flow and/or the short circuit flow can pass around the operating element.
German Patent Publication DE 44 09 547 C2 teaches a basic thermostatic valve. The thermostatic valve comprises an expansion element which actuates movement of two valve plates to open or close connection openings of the thermostatic valve. A radiator flow of the cooling system coolant starting from the radiator and a short circuit flow of the cooling system coolant from a short circuit line can pass around the expansion element. In intermediate positions of the valve the cooler radiator flow of the cooling system coolant and the warmer short circuit flow of the cooling system coolant can be mixed. When the radiator flow is blocked, whereby coolant from the engine passes only via the short circuit line to the thermostatic valve, a section of the expansion element lies in a cooler area of the coolant that is in direct fluid communication with the radiator. The expansion element can be electrically heated in order to influence the regulating curve of the thermostatic valve. Relatively large positioning forces are necessary in order to close the valve plates against a coolant flow through the thermostatic valve.
It is accordingly an object of the present invention to solve the technical problem of improving the control dynamics of a thermostatic valve.
The present invention provides to this end a thermostatic valve, especially for the cooling system of a vehicle with an internal-combustion engine, comprising a valve housing, a temperature-sensitive operating element in an operating element housing affixed stationarily on the valve housing, and a closure member that can be adjustably controlled by the operating element. The valve housing comprises a radiator connection opening, an engine connection opening and an additional auxiliary connection opening, whereby a radiator flow of the cooling system coolant can be established between the radiator connection opening and the auxiliary connection opening, a short circuit flow of the cooling system coolant can be established between the engine connection opening and the auxiliary connection opening, and the radiator flow and/or the short circuit flow can pass around the operating element.
According to the present invention, a fluid connection between the radiator connection opening and the operating element is interrupted and the engine connection opening is opened in a first position of the closure member, and in a second position of the closure member, the radiator connection opening is opened and a fluid connection between the engine connection opening and the operating element is interrupted. As a result of this arrangement, only the short circuit flow of the cooling system coolant passes around the operating element in its first position since the radiator flow of the cooling system coolant is already blocked upstream from the operating element and, in the case of a reverse flowthrough, upstream from the radiator. Accordingly, there is no fluid connection between the operating element and the vehicle radiator in the first position. Thus, in the first position of the closure member, a rapid heating of the operating element by the warmer short circuit coolant flow is achieved. As a consequence, after sufficient heating of the coolant of the short circuit coolant flow in the short circuit circulatory system, the cooler radiator flow of the cooling system coolant from the cooling circuit is rapidly mixed in, resulting in a control dynamics of the thermostatic valve that is improved over the state of the art. Only the radiator coolant flow passes around the operating element in its second position because the engine connection opening is closed upstream from the operating element and, given the reverse flowthrough, upstream from the engine, and there is no fluid connection between the engine block and the operating element. This results in lesser disturbing influences in the regulating of the coolant circuit as a function of the coolant temperature of the cooler radiator coolant flow. For example, an expansion element can be provided as temperature-sensitive operating element, that can also be combined with an actuating drive.
According to a further development of the present invention, a section of the operating element, around which the warmer short circuit coolant flow can not flow in the first position, comprises a thermal insulation. As a result, the operating element can be better insulated against cooler areas into which sections of the operating element can extend. The heating of the operating element by the warmer short circuit coolant flow can take place even more rapidly by such an insulation.
A further feature of the invention provides that the closure member is designed as a closure ring in the preferred form of an annular slide valve. The provision of a closure ring makes possible a slight pressure drop in the first and second positions as well as in all intermediate positions of the closure member in the thermostatic valve. Relatively lower adjusting forces are sufficient in order to shift the closure ring, in comparison to a plate valve. Even in the case of a rapid opening of the closure ring its tendency to oscillate is low.
A further aspect of the invention is that the closure ring provides for an inner coolant flow. Such an inner coolant flow can be used advantageously for a heating circuit, resulting in a compact arrangement of the thermostatic valve. For reasons of comfort, a heating circuit is not closed even when the engine is cooler, so that the provision of a closure ring with inner coolant flow that does not have to be closed represents a compact and simple arrangement.
A further feature of the invention is that an annular sealing surface is provided on the valve housing on which surface a front side of the closure ring rests in one of the positions. The annular sealing surface and the front side of the closure ring are beveled relative to a longitudinal axis of the closure ring and generally extend parallel to one another. Substantially parallel, oblique sealing surfaces make possible a gentle opening of the closure ring, which avoids pressure jolts. The oblique sealing surfaces, that are parallel to one another, advantageously extend parallel to the direction of coolant flow. The beveled front side of the closure ring can be realized in a simple manner by means of an obliquely extending bend or offset of the closure ring.
In a further development of the invention, the closure ring comprises an annular baffle extending from the front side of the closure ring. The coolant flow in the thermostatic valve can be guided with such a baffle, as a result of which a low pressure drop can be achieved and the occurrence of oscillations and pressure spikes is avoided.
A thermal insulation is advantageously provided in the area at which the operating element is fastened to the valve housing. As a result, the valve-housing temperature exerts only a slight influence on the operating element and the position of the closure ring and accordingly the valve housing can be manufactured from a heat conductive material, e.g., from aluminum. Such a thermal insulation also insulates against coolant areas in the particular end positions of the closure ring.
A further feature of the invention provides that the operating element can be heated by an energy source other than the circulating engine coolant. This makes it possible to influence the regulating curve of the operating element. For example, an electrically heatable expansion element can be provided that can also be realized in combination with an actuating drive.
In a further development of the invention, the closure member comprises a guide bolt shiftably guided in the valve housing. A guiding of the closure member is achieved therewith both by the operating element and also by the guide bolt. This results in a good guidance of the closure member that is advantageous especially on account of the customarily strong pre-tensioning of the closure member by pressure springs. In turn, a fluttering or clamping of the closure member is avoided. In particular, a two-sided guidance of a closure ring is advantageous since the closure ring is guided on the one side by the operating element and on the other side by the guide bolt.
A further measure of the invention provides a sensor for detecting the position of the closure member. As a result, the position of the closure member can be detected and transmitted further to a control device or diagnostic device. The regulating curves of the thermostatic valve can be influenced in a purposeful manner in combination with a control device and a heatable operating element or an actuating drive.
The housing is advantageously a component of a coolant pump housing. As a result of this measure, no additional housing is required for a thermostatic valve.
In a further development of the invention, the radiator coolant flow can be established from the radiator connection opening to the auxiliary connection opening or in the reverse direction, and the short circuit coolant flow can be established from the engine connection opening to the auxiliary connection opening and in the reverse direction. The thermostatic valve of the invention can be used therewith for inlet-regulated cooling systems as well as for outlet-regulated cooling systems.
Further features and advantages of the invention will be understood from the following description of preferred embodiments of the present invention in conjunction with the drawings and the accompanying claims.